Process for the production of 5-nitro-1 4-dihydroxy-anthraouinone

ABSTRACT

5-NITRO-1,4-DIHYDROXY-ANTHRAQUINONE IS PRODUCED BY NITRATING 1-HYDROXY-10-CHLOROANTHRAQUINONE (4,9) IN AN INORGANIC ACID SOLVENT AND HYDROLYZING THE RESULTANT 1-HYDROXY-5-(OR 8-)NITRO-10-CHLORO-ANTHRAQUINONE-(4,9).

United States Patent US. Cl. 260351 4 Claims ABSTRACT OF THE DISCLOSURES-nitro-1,4-dihydroxy-anthraquinone is produced by nitrating1hydroxy-10-chloroanthraquinone (4,9) in an inorganic acid solvent andhydrolyzing the resultant l-hydroxy-S-(or8-)nitro-10-chloro-anthraquinone-(4,9).

This invention relates to S-nitro-1,4-dihydroxy-anthraquinone. It isknown that 5-nitro-1,4-dihydroxy-anthraquinone can be obtained byheating a mixture of 1,5- and 1,8-dinitroanthraquinone innitrite-containing borosulphuric acid at about 200 C. (cf. German PatentNo. 90,041). However, according to such process, 5-nitro-l,4-dihydroxy-anthraquinone is obtained only in a low yield and with aninsuflicient degree of purity.

According to the present invention, 5-nitro-1,4-dihydroxyanthraquinoneis obtained in a good yield and with a high degree 0 f purity bynitrating l-hydroxy-lO-chloroanthraquinone-(4,9) in an inorganic acidsolvent to give l-hydroxy-S- (or 8) nitro-10-chloroanthraquinone- (4,9and hydrolising the latter in known manner to give 5-nitro-l,4-dihydroxy-anthraquinone.

The l-hydroxy-l0-chloro-anthraquinone-(4,9), Greens substance, can beprepared, for example, by prolonged heating of quinizarin with thionylchloride (A. Green, Journal of the Chemical Society, 1926, p. 1431).

Examples of inorganic acids used in the present process are sulphuricacid which can contain S0 chlorosulphonic acid, nitric acid, andmixtures thereof. Boric acid is advantageously also present. Theconcentration of the solutions can be varied Within wide limits, but isgenerally carried out in a 3- to -fold amount of solvent, advantageouslyin the presence of a /2- to 1-fold amount of boric acid, all based onthe weight of the starting material. The nitric acid can be used for thenitration in the stoichiometric amount or in a small (about 10-30%)excess.

The temperature during nitration should be kept as low as possiblesince, from about C. onwards, the hydrolysis ofl-hydroxy-lO-chloro-anthraquinone-(4,9) forming quinizarin takes placeas an interfering side reaction. Consequently, temperatures of about 15C. to about +15 C. are preferred.

The hydrolysis of l-hydroxy-S-(or 8-)nitro-10-chloroanthraquinone-(4,9)to give the 5-nitro-1,4-dihydroxyanthraquinone is preferably carried outin boric acid-containing sulphuric acid. It may be efiected either afterisolating the intermediate product or, advantageously, without isolationimmediately following the nitration. For this purpose, the reactionmixture is stirred, erg. after completion of the nitration, either for aprolonged time at a low temperature (e.g. at +10 C. for 24 hours), or itis heated at 70-80 C. for a short time. The excess of nitric acidpresent can previously be destroyed by a suitable reducing agent, e.g.hydrazinium hydrogen sulphate.

After conventional working up, a crude product, which contains about 90%S-nitro-1,4-dihydroxy-anthraquinone, is obtained in a satisfactoryyield.

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It is surprising and could not be foreseen that l-hydroxy-10-chloro-anthraquinone-(4,9) can be nitrated in such a smooth mannerwithout oxidation, in particular, since it is known from German Pat. No.272,299 that 1,4-dihydroxy-anthraquinone itself yields3-nitro-1,2,4,trihydroxyanthraquinone by nitration in sulphuric acidwith oxidation, but cannot be nitrated at all in boric acid-containingsulphuric acid.

5-nitro-1,4-dihydroxy-anthraquinone prepared according to the processdescribed above is a valuable intermediate for dyestuffs. It can bereduced in known manner, e.g. with sodium sulphide, to give5-amino-1,4-dihydroxyanthraquinone which, in turn, is a valuableintermediate product.

The parts and percentages given in the examples are parts by weight, thetemperatures are given as degrees centigrade C.).

This intermediate product can be employed to produce known dyestulfs asdescribed in US. Pat. 2,053,273.

Example 1 50 parts l-hydroxy 10 chloro anthraquinone-(4,9) [Greenssubstance containing about 3% quinizarin] are introduced at l0 to 0within 30 minutes into a solution of 30 parts boric acid in 460 partssulphuric acid (96%) and dissolved. 57 parts of a mixed acid 28% HNO 56%H 80 16% H O are then allowed to run into the solution at below 0, themixture is cooled to 10 and stirred at this temperature for two hours.10 parts hydrazine sulphate are added at below 0 to decompose the nitricacid, the mixture is heated within 4 hours up to 80 and this temperatureis maintained for 30 minutes. The melt is diluted with 1000 parts water,briefly heated to boiling temperature, filtered off with suction whilehot, and washed with hot water until neutral. After drying, 54 partsS-nitro-l,4-dihydroxy-anthraquinone are obtained which, besides about 3%1,4-dihydroxy-zanthraquinone, still contains a small amount of6-nitro-1,4-dihydroxy-anthraquinone. If the process is carried outaccording to this example, but without the addition of hydrazinesulphate, then a crude product is obtained in the same quantity whichadditionally contains a small amount of 2-(or 3-)chloro-S-nitro-1,4-dihydroxy-anthraquinone as impurity.

Example 2 20 parts l-hydroxy 10 chloro-anthraquinone-(4,9) (Greenssubstance containing about 3% quinizarin) are introduced at between l0and 5" into a solution of 10 parts boric acid in parts nitric acid(96%). The mixture is cooled to 10 and kept at this temperature for onehour. The melt is poured on to 500 parts of ice, the product is filteredoff with suction and Washed with water until the reaction is neutral.After drying, there are obtained 21 parts l-hydroxy-S-(or8-)nitro-lO-chloro-anthraquinone-(4,9) which yields by heating at for 30minutes in parts 10% boric acid, after working up as described above inExample 1, 19.5 parts 5-nitro-1,4-dihydroxy-anthraquinone.

Example 3 50 parts l-hydroxy 10 chloro-anthraquinone-(4,9) [Greenssubstance containing about 3% quinizarin] are introduced at 10 to 0 into460 parts sulphuric acid (96%), 57 parts of a mixed acid (28% HNO 56% H80 16% H O) are then added dropwise at below 0 within 20 minutes, andstirring is continued at 0 for 20 minutes. The reaction mixture isstirred into 1000 parts of water, the product is filtered oif withsuction, washed until neutral and dried. There are obtained 55 partsl-hydroxy-S-(or 8-)nitro-10-chloro-anthraquinone (4,9) which yield,after hydrolysis in boric acid-containing sul- 4 phuric acid accordingto Example 2, 49 parts 5-nitro-1,4- 3. Process of claim 2 wherein theinorganic acid condihydroXy-anthraquinone. tains boric acid.

What is claimed is: 4. Process of claim 2 wherein the hydrolising iscon- 1. A compound selected from the group consisting of ducted in thepresence of sulphuric acid which contains l-hydroxy-S-nitro 10chl0ro=anthraquinone-(4,9) and 5 boric acid. l-hydroxy-S-nitro-lO-chloroanthraquinone- (4,9

2. A process for the production of 5-nitro-1,4-dihy- References C tedroxy-anthraqninone comprising, in sequence, the steps of: UNITED STATESPATENTS (A) nitrating, at a temperature of about 15 C. to

about +15 C., l-hydroxy-10-chlor0anthraquinone- 10 3082218 3/1963Buxbaum et a1 (4,9) in an inorganic acid solvent selected from sul-OTHER REFERENCES furic 'acid, sulfuric acid containing S0 chlorosul-Green, h Soc 192 1431 tonic acid, nitric acid and mixtures thereof, toyield :I-hYdIOXY-S-(OI' 8-) nitro-lO-chloroanthraquinone- LEWIS GOTTS, Pmary E ami r (4,9); and 15 R. GERSTL Assistant Exam'ner (B) hydrolisingthe l-hydroxy-S-(or 8-) nitro-lO-chlo- 1 roanthraquinone (4,9) toS-nitro 1,4 dihydroxy- US. Cl. X.R. anthraquinone. 260-380, 383

